Hello doctor, I am 28 years old male and I am facing small red spot on my chest, neck, shoulder and back but mainly on chest from last 6 months, after appearing they stay 5-6 days and goes out but before going they became blister bump with small yellow pus. They does not itch usually. What are they. Why they are appearing? Should I test my blood? If yes then which test? If it's problem related to blood kindly advise me Please.